Early first-trimester detection of thoracopagus conjoined twins using transvaginal 2D/3D ultrasound and augmented reality

Monochorionic monoamniotic (MCMA) twin pregnancy is an uncommon pregnancy condition associated with an increased risk of obstetric complications compared with singleton pregnancy and other types of multiple gestation. In such pregnancy, early ultrasonographic assessment of fetal anatomy allows early identification of structural anomalies such as conjoined twins1; prompt and accurate prenatal diagnosis of this condition is crucial for timely patient counseling and appropriate clinical care, but diagnosis < 12 weeks’ gestation remains challenging2. We report a rare case of thoracopagus conjoined twins with a single fused heart, diagnosed exceptionally early in the first trimester by means of two-dimensional ultrasound (2D-US) and complementary three-dimensional ultrasound (3D-US) with post-processing augmented reality (AR) visualization.